1. Field of the Invention
This invention is directed to tire overlay compositions that reduce tire noise.
2. Description of the Related Art
There is a continued need for improved passenger car and truck tire performance. Key performance attributes include noise, handling, wear, rolling resistance, and ride comfort. Reduced tire noise is becoming an industry focus as tire companies strive to reduce noise radiated from automobile and truck tires. For example, the European Union is putting in place legislation to significantly reduce pass-by noise from tires.
Certain fibers have been utilized in high performance tire production. U.S. Patent Publication No. 2002/0069948 teaches the use of short fibers at angles that are largely perpendicular to the tire surface. The purpose of these constructions is said to be improvement in handling and/or acceleration. U.S. Patent Publication No. 2007/0221303 utilizes short fibers in a construction that enhances the tread directional stiffness. These fibers are said to be aligned somewhat perpendicular to the longitudinal, circumferential direction of the tread. U.S. Pat. No. 4,871,004 discloses aramid-reinforced elastomers where short, discontinuous, fibrillated aramid fibers are dispersed in rubber. The arrangements disclosed in this patent are said to maximize lateral (axial or circumferential) stiffness and modulus. These arrangements, however, are not taught to be beneficial for noise reduction.
U.S. Patent Publication No. 2010/0236695 pertains to tires having a composite tread block which comprises a cured elastomer and from 0.1 to 10 parts per hundred parts by weight of the elastomer of fibers characterized as having a tenacity of at least 6 grams per dtex and a modulus of at least 200 grams per dtex. A major portion of said fibers are oriented in a direction such that noise arising from tire tread contacting the road surface is reduced.